As far as I know it's all players that have it, you get xp for Slomo for doing tasks in the Slomo screen, xp for collecting coins, spinning slots and doing the city tasks as well.
Quick update for anyone who saw my last post about Macadam.
I've now cashed out another £60, so that's £90 total so far.
I'm still just using it alongside my normal routine. Walking the dog, commuting, and getting my daily steps in. I also earn extra coins now and then by playing a few games or doing the odd survey when I've got some spare time.
If you're already walking every day, it's worth checking out. It won't make you rich, but it's nice getting a bit of extra money for something you're doing anyway.
If you decide to give it a go, use my code Y9HYH9 when you sign up and you'll get 1,000 coins to start with.